Means for mounting solid propellant in a rocket motor

Abstract

A solid propellant grain is held within a rocket motor case in a substantially stress-free manner. The grain is not bonded to the case itself but is bonded to a sleeve which has lateral protrusions or convolutions on its exterior which fit loosely and unattached into similar convolutions in a sleeve bonded to the interior of the case. The sleeve bonded to the propellant is made of a polymer having substantiallythe same elastomeric qualities as the propellant itself so that stresses are not created in the propellant at the bond. Physical shock or distortion of the propellant and thermal expansion or contraction of it create changes in dimension which are absorbed principally by the clearance gap between the convoluted surfaces of the sleeves and therefore substantially no cracking stresses are produced in the propellant itself.

What is claimed is: 
     
       1. In a rocket motor containing a solid propellant, a thrust chamber case having an annular inner wall, an annular first sleeve having an outer wall bonded to the inner wall of the case and an inner wall having at least one convolution, an annular second sleeve having an inner wall bonded to the solid propellant and an outer wall having at least one convolution which matches that of the first sleeve with the convolutions of each meshed but unattached throughout the propellant's length and spaced therefrom by a clearance gap, and the material of the second sleeve being polyisoprene. 
     
     
       2. In a rocket motor containing a solid propellant, a thrust chamber case having an annular inner wall, an annular first sleeve having an outer wall bonded to the inner wall of the case and an inner wall having at least one convolution, an annular second sleeve having an inner wall bonded to the solid propellant and an outer wall having at least one convolution which matches that of the first sleeve with the convolutions of each meshed but unattached throughout the propellant's length and spaced therefrom by a clearance gap, and the convolutions sinusoidal in longitudinal cross sectional profile. 
     
     
       3. In a rocket motor containing a solid propellant, a thrust chamber case having an annular inner wall, an annular first sleeve having an outer wall bonded to the inner wall of the case and an inner wall having at least one convolution, an annular second sleeve having an inner wall bonded to the solid propellant and an outer wall having at least one convolution which matches that of the first sleeve with the convolutions of each meshed but unattached throughout the propellant's length and spaced therefrom by a clearance gap, and the convolutions in a saw tooth longitudinal cross sectional profile. 
     
     
       4. In a rocket motor containing a solid propellant, a thrust chamber case having an annular inner wall, an annular first sleeve having an outer wall bonded to the inner wall of the case and an inner wall having at least one convolution, an annular second sleeve having an inner wall bonded to the solid propellant and an outer wall having at least one convolution which matches that of the first sleeve with the convolutions of each meshed but unattached throughout the propellant's length and spaced therefrom by a clearance gap, and the convolutions in a square tooth longitudinal cross sectional profile. 
     
     
       5. In a rocket motor containing a solid propellant, a thrust chamber case having an annular inner wall, an annular first sleeve having an outer wall bonded to the inner wall of the case and an inner wall having at least one convolution, an annular second sleeve having an inner wall bonded to the solid propellant and an outer wall having at least one convolution which matches that of the first sleeve with the convolutions of each meshed but unattached throughout the propellant's length and spaced therefrom by a clearance gap, and the convolutions in the sleeves in the form of similar helicies of constant pitch to form a mating screw thread. 
     
     
       6. The invention set forth in claim 5 with a stop key inserted in keyway slots in both the first and second sleeves and bridging the gap, whereby relative rotation between the first and second sleeves is prevented.